Endoscopic surgery has gained wide acceptance as an improved and cost effective technique for conducting certain surgical procedures. In endoscopic surgery, a trocar, which is a pointed piercing device, is inserted into the body with a cannula placed around the trocar. After the trocar pierces the abdominal wall, it is removed and the cannula remains in the body. Through this cannula, endoscopic procedures are possible. Often, multiple openings are produced in the body with a trocar so that an endoscopic instrument may be placed in one cannula, appropriate viewing and illuminating means placed in another cannula and so forth. As more is learned about endoscopic surgical procedures and more instruments developed, the type of procedures that may be performed will increase. Presently, some procedures include gall bladder, diagnostic procedures, bowel resections, joint repair, tissue repair and various sterilization procedures.
In many of these endoscopic procedures, it is necessary to cut tissue or coagulate tissue or sometimes both. A number of devices have been developed for cutting tissue such as knives and lasers and a number of devices have been developed for coagulating tissue, again using lasers or cauterizing devices. When lasers have been used to either cut or coagulate tissue, the laser is outside the body and a laser beam is delivered within the body cavity through appropriate fiber optics. By delivering the laser beam through a fiber optic, considerable energy is required to obtain the necessary power at the distal tip of the fiber optic. This type of delivery also causes the laser beam to lose spatial coherence and, hence, makes it impossible to efficiently focus the light to a diffraction limited spot.
It is an object of the present invention to provide a laser beam within the body cavity that has excellent spatial coherence. It is a further object of the present invention to provide a laser beam at the distal tip of an endoscopic instrument from relatively low energy lasers. It is yet another object of the present invention to provide a laser beam that may be used to both coagulate and cut tissue in an endoscopic procedure.